The puprose of this proposal is to study the possibility that alterations of the cytoskeleton by either the direct or indirect action of the SRC gene product of RSV-transformed cells could lead to the pleiotropic effects that are characteristic of the transformed phenotype. First, the relationship between the cytoskeleton and specific cell functions, in particular, hormone-receptor binding and cell adhesion will be determined. The effect of disruption of the cytoskeleton on the binding of alprenolol, a beta-adrenergic agonist, to its receptors in the plasma membrane will be examined. I will attempt to localize the receptor in relation to the cytoskeleton by electron microscopy and to examine the effect of Triton extraction on bound beta-adrenergic hormone. To study cell adhesion, the involvement of the cytoskeleton in the spreading of cells in cytochalasin B (CB) will be determined by electron microscopy techniques including immunocytochemistry of cells sectioned perpendicular to the substrate. Also the relationship between the cytoskeleton and fibronectin in cells spreading in CB will be studied. The cytoplasmic targets for SRC will be examined concentrating on the characterization of the alteration of the 10nm filaments following transformation with RSV. This characterization will be both biochemical, studying the 10nm filament protein both before and after transformation with RSV and biological, examining the relationship between the SRC gene product and the alteration of 10nm filaments through the use of various mutants of RSV. Finally, I will examine how the effects of SRC on the cytoskeleton may alter hormone-receptor binding and cell adhesion.